In conventional practice, exposure apparatuses that use microlens arrays have been used as laser annealing apparatuses for reforming an amorphous silicon film into a polysilicon film by irradiating the amorphous silicon film with laser light and melting and solidifying the amorphous silicon film by the heat of the laser light. Such exposure apparatuses have been used as exposure apparatuses for photolithography wherein a mask image is projected and exposed on a resist film, and a resist pattern is formed by a subsequent developing process. The invention disclosed in Patent Document 1 is an example of an exposure apparatus in which the microlens array is used.
In the exposure apparatus disclosed in Patent Document 1, an object 101 to be exposed is placed on a stage 100, and a photomask 102 and a microlens array 106 are arranged above the object 101 to be exposed, as shown in FIG. 4. Exposure light from a light source 111 is focused by a collimator lens 110 and radiated onto the photomask 102. The photomask 102 contains a light-blocking film 104 having openings 105, the film formed on the top surface of a transparent substrate 103; and numerous microlenses 107 arranged two-dimensionally are formed on the bottom surface of the transparent substrate 103, constituting the microlens array 106. Exposure light transmitted through the openings 105 of the light-blocking film 104 are transmitted through the microlenses 107 of the microlens array 106, made to converge, and imaged on the object 101 to be exposed. The photomask 102 and the microlens array 106 are supported by a mask stage 108.
FIG. 5 is a cross-sectional view showing a projection-exposure type exposure apparatus using a conventional microlens array. A resist film 2 is formed on a substrate 1, and the substrate 1 is conveyed below a microlens exposure apparatus. A conventional microlens exposure apparatus is provided with a microlens array 3 formed by two-dimensionally arranging numerous microlenses 3a, and a mask 4 is arranged above the microlens array 3. The microlens array 3 is formed from a transparent quartz substrate, and the microlenses 3a are machined into the transparent quartz substrate of the microlens array 3. The mask 4 is configured by bonding a Cr film 5 to the bottom surface of the transparent substrate of the same material as the microlens array 3, and holes 5a through which laser light passes are formed in the Cr film 5. Portions of the mask 4 other than the holes 5a are covered by the Cr film 5, constituting light-blocking portions that prevent laser light from passing through. Both ends of the microlens array 3 are bent so as to extend towards the mask 4, and the end surfaces of these ends are bonded to the mask 4 above. The mask 4 and the microlens array 3 are thereby fixed in place.
In a conventional microlens exposure apparatus configured in this manner, when the laser light for exposure is radiated onto the mask 4, the laser light that has passed through the holes 5a in the mask 4 is irradiated onto the microlenses 3a of the microlens array 3 and the microlenses 3a cause the light to converge on the resist film 2 on the substrate 1. A pattern to be projected is formed in the holes 5a, and when the laser light is transmitted through the holes 5a and radiated onto the resist film 2, the pattern is projected onto the resist film 2.
In the conventional projection-exposure type exposure apparatus using a microlens array, positional alignment of the substrate 1 with the mask 4 and the microlens arrays 3 has been performed using a substrate 1a for adjustment shown in FIG. 6. Alignment marks 11 are formed at both ends in the bottom surface of the mask 4 where there are no microlens arrays 3, and cameras 10 are arranged below the alignment marks 11 and also below the transparent substrate 1a for adjustment. Transparent supports 30 are provided on the substrate 1a for adjustment at positions facing the alignment marks 11, and marks 31 are formed on these transparent supports 30. The mask 4 and the microlens arrays 3 are positioned relative to the substrate 1a for adjustment so that the alignment marks 11 on the bottom surface of the mask 4 and the marks 31 on the supports 30 coincide within the same field of vision as seen through the cameras 10. Thus, in the substrate la for adjustment, positional adjustment between the production substrate 1 and the mask 4 is performed by aligning the positions of the mask 4 and the substrate 1a. 